This invention relates to wind power energy and, more particularly, to foldable turbine blades for simplified transportation in construction of wind towers and reduction of stress loads on the turbine blades during extreme wind conditions.
Wind power is a rapidly growing segment of the electric power generation industry. A single wind tower utilizes a wind turbine blade to input rotational energy directly into an electric generator to generate and supply electricity to a power grid. The potential energy production of the wind tower corresponds directly to the area swept by the wind turbine blades during rotation. An incremental increase in the length of the wind turbine blades produces a square exponential increase in potential energy production.
Conventional wind turbine blade designs have sought to take advantage of the exponential increase in potential energy production simply by using longer length turbine blades. Manufacturing longer wind turbine blades, however, may not account for the additional mass of the longer length or for the additional expenses associated with manufacturing and transporting longer length turbine blades. Wind turbine blade mass and expense increase with the cube of the wind turbine blade length. Since the increase in potential energy production only increases with the square of the wind turbine blade length, simply making longer length wind turbine blades may not be feasible or economical compared to the cubic relation of length to mass and expense. Furthermore, the added mass may in turn contribute to stress loads on the wind turbine blades and decrease the life of the wind turbine blades.
Another wind turbine blade design utilizes an extendable blade end portion to extend the wind turbine blade length. The extendable blade end portion extends and retracts co-linearly with a blade base portion. The extendable blade end portion may require additional machinery to retract and extend. The additional machinery may add mass and expense to the wind turbine blade and therefore negate the increase in potential energy production from the increased length of the wind turbine blade. Additionally, the added mass may in turn contribute to stress loads on the wind turbine blades and decrease the life of the wind turbine blades.
Accordingly, a turbine blade that provides increased blade length with minimal added mass and machinery is needed.